MAKING IT USEABLE    Interpreting Estimates       Confidence Limits

The confidence limits for the national sample are calculated by taking 1.96 times the sampling error for 95 percent and 2.58 times the sampling error for 99 percent confidence limits, and adding and subtracting the resulting value from the estimated population mean or total to obtain the range.

Table 10

		95% Confidence Interval		99% Confidence Interval
Characteristic Estimated	Estimate	Lower Bound	Upper Bound	Lower Bound	Upper Bound
Average Household Size	2.584	2.564	2.604	2.558	2.61
Vehicle per Household	1.779	1.765	1.793	1.761	1.797
Work Trips per HH per Day	2.79	2.741	2.839	2.725	2.855
Workers per Household	1.299	1.287	1.311	1.284	1.314
Annual Miles per Vehicle	12226	12096	12356	12055	12397
Bicycle Trips per Day per HH	0.082	0.074	0.090	0.072	0.092

---